Automatic telephone system



C. L. GOODRUM.

AUTQMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAR. 28. 1918.

1,364,106, Patented Jan. 4, 1921,

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' Char/es L. Gaodru/o C. L. GOODRUM.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAR. 28, I918.

Patented Jan. 4, 1921.

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means whereby UNITED STATES PATENT OFFICE.

CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y. 7

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Jan. 4, 1921.

To all whom it may concern:

Be it known that I, CI-iARLns L. GooDRUM, a citizen of the United States, residing at New York, in the county of New York, State of New York, have invented certa n new and useful Improvements in Automatic Telephone Systems, of which the follow ng is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems in which subscribers lines are interconnected by means of automatic switching apparatus.

In'automatic telephone systems a calling party very often wishes to converse 1n succession with several different parties in the same distant exchange and in order to establish such connection he has to set up a complete connection each time.

The object of this invention is to provide a calling party may establish a connection to a telephone exchange and then establish any number of connections with parties in said called exchange without having to set up a complete connection each time from the calling exchange to the called exchange.

In accordance with this object one feature of the invention is the provision of means for releasing the automatic switching apparatus of the called exchange without releasing the automatic switching apparatus used in establishing a connection between the calling exchange and the called exchange.

In accordance with this object another feature of the invention is the provision of means for informing an operator that a talking connection between two parties has been broken down and that the calling party wishes to have another talking connection established to another line in the called exchange.

Other features of the invention will appear in the following specification and claims.

Referring to the drawings, Figures 1 and 2 diagrammatically represent a semi-automatic private branch exchange telephone svstem embodying the features ofthis 1nv enticn. Fig. 1 represents a calling subscribers line, a line switch, a selector circuit at one exchange and a trunk terminating in a plug at anpperators 'POSltlOIl in another exchange; Fig. 2 represents a connector circuit and a called subscribers line at the second exchange; and Fig. 3 diagrammatically represents a portion of a full automatic telephone system embodying certain of the features of this invention. In Fig. 3 a repeater circuit, and a trunk which extends to a connector circuit similar to that shown in Fig. 2, are shown.

It will be assumed that the subscriber 100 wishes to establish a connection with subscriber 222 in a distant exchange. Subscriber 100 by removing the receiver from its switchhook causes the operation of the line switch 101, and then by operating his dial 108 causes in a well-known manner the selector switch 102 to select an idle trunk ,leading to an operators position at the distant exchange. A circuit is then closed from grounded battery, through the left-hand winding of relay 104, lower left-hand winding of repeating coil 105, lower brush of selector switch 102, lower brush of line switch 101, loop of substation 100, upper brush of line switch 101, upper brush of selector switch 102, upper left-hand winding of repeating coil 105, right-hand winding of relay 104 to ground. Relay 104 becomes energized and closes a circuit from grounded battery, through winding of relay 106, right-hand armature and front contact of relay 104 to ground. Relay 106 energizes and closes a circuit from grounded battery, through winding of relay 107, left-hand armature and front contact of relay 106 to ground.

Relay 104 also closed a circuit from grounded battery, through lamp 108, righthand armature and back contact of relay 109, armature and front contact of relay 104 to ground. Lamp 108 becomes lighted and notifies the operator that there is a call waiting on the trunk associated with plug 110. The operator depresses her listening key 11 which connects her head set (not shown) across the conductors 112 and 113. The operator then ascertains the number of the desired called line from the calling subscriber. She then depresses her sending key 115 and also inserts the plug 110 into a jack 114 associated with a trunk which leads to a connector switch having access to the called line. A circuit is now completed from grounded battery, through the left hand winding of relay 200, conductor 201, tip of ack 114, tip of plug 110, upper spring and alternate contact of key 115, impulse 117, alternate contact of the lower spring of key 1l5,'ring of plug 110, ring of jack 114, conductor 202, right-hand winding of relay 200 to ground. Relay 200 energizes and completes a circuit from grounded battery, through winding of relay 203, armature and .front contact of relay 200 to ground.

The operator now operates her sending device 117 twice to produce two series of interruptions in the circuit of the line relay 200. In response to the first interruption of the first series, relay 200 deenergizes and closes a circuit from grounded batte through the winding of relay 204, righthand armature and front contact of relay 203, armature and back contact of relay 200' to ground. Relay 204 energizes and closes a circuit for the escapement magnet 205 from grounded battery through the winding of magnet 205, side-switch arm 206, inner right-hand armature and contact of relay 204, armature and back contact of ringing relay 207 to ground. The initial deenergization of relay 200 also closes a circuit from grounded battery through the winding of primary magnet 208, side-switch arm 209, right-hand armature and front contact of relay 203, armature and back contact of relay 200 to ground. Magnet-208 becomes energized and moves the connector switch one step in its primary movement. Magnet 208 is energized in a similar manner to continue the primary movement of the connector switch each time the line relay 200 is deenergized by each interruption of the first series of interruptions. Relays 203 and 204 are made slow to release so that they hold their armatures attracted during the primary movement of the connector switch.

After the last interruption of the first series, relay 200 remains energized for a sufficient length of time to allow the slow-torelease relay 204 to retract its armatures and open the circuit of the escapement magnet 205. Magnet 205 deenergizes and moves the side-switch arms into their second position. In response to the first interruption of the second series, relay 200 deenergizes and causes the energization of relay 204 in the same manner as described. Relay 204 closes a circuit from grounded battery, through winding of escapement magnet 205, sideswitch arm 206 (position 2), inner righthand armature and contact of relay 204, armature and contact of relay 207 to ground. The deenergization of relay 200 also closes a circuit from grounded battery through the winding of the secondary magnet 210, sideswitch arm 209 to ground at the armature and back contact of relay 200 over the circuit previously described. Magnet 210 becomes energized and moves the connector switch one step in its secondary movement. Magnet 210 is energized in a similar manner length of time to allow slow-to-release relay 204 to deenergize.

It will first be assumed that the called line is idle; in which condition no ground is found upon the test terminal 211 thereof.

Relay 204 therefore remains deenergized and 7 allows the escapement magnet 205, which is also slow to release, to deenergize and move the side-switch arms into their third positions.

In position 3 of the side switch, ground is connected through the side-switch arm 217, brush 214, to test terminal 211 and the multiples thereof to render the called line busy.

In position 3 of the side switch, a circuit is also closed from grounded battery, through winding of relay 204, side-switch arm 209, conductors 218 and 219, armature and front contact of relay 200 to ground. Relay 204 energizes and closes the above traced circuit for the escapement magnet 205. Magnet 205 becomes energized and closes a ringing circuit from a grounded source of ringing current 220, winding of marginal ringing relay 207, armature and contact of escapement magnet 205, sideswitch arm 221 (position 3), brush 215, terminal'212, apparatus at substation 222, terminal 213, brush 216, side-switch arm 223 (position 3), conductor 219, armature and front contact of relay 200 to ground. The current flowing over'this ringing circuit is insuflicient to cause the marginal ringing relay 207 to attract its armature, but is sufficient to operate the high resistance bell at the substation 222.

lVhen the subscriber at substation 222 removes his receiver from its switchhook, a shunt isplaced around the bell of the called substation so that sufficient current for operating the relay 207 flows through the ringing circuit. Relay 207 energizes and opens the circuit of the escapement magnet 205. Magnet 205 deenergizes and moves the side- 'switch arms into their fourth positions.

Current is now supplied to the called line from grounded battery, left-hand winding of relay 224, side-switch arm 223 (position 4), brush 216, terminal 213, loop of substation 222, terminal 212, brush 215, side-switch arm 22 1 (position 4), right-hand winding of relay 224 to ground. Relay 224 energizes and closes a circuit for energizing relay 204 from grounded battery, through winding of relay 204, armature and front contact of relay 224, armature and front contact of relay 200 to ground.

The operator after actuating her sending device the second time releases her sending key 1.15 so that the relay 200 is held energized over a circuit from grounded battery through the left-hand winding of relay- 200, conductor 201, tip of jack 114, tip of plug 110, normal contact of the upper spring of key 115, conductor 112, upper right-hand winding of repeating coil 105, winding of relay 109, outer right-hand armature and contact of relay 106, lower right-hand winding of repeating coil 105, conductor 113, normal contact of the lower spring of the key 115, ring of plug 110, ring of jack 11 1, conductor 202, right-hand winding of relay 200 to ground. Relay 109 energizes and opens the circuit of lamp 108.

The subscribers lines are now connected for conversation. Upon the termination of conversation, the subscriber at substation 100 replaces his receiver upon its switchhook, thereby opening the circuit of relay 10%. Relay 1041 deenergizes and causes the restoration of the line switch 101 and the selector switch 102 in the well-known manner. The deenergization of relay 1041 also opens the circuit of relay 106. Relay 106 deenergizes and closes a circuit from grounded battery, through the left-hand winding of relay 118, armature and contact of relay 107, left-hand armature and back contact of relay 106, to ground. Relay 118 energizes and closes a locking circuit for itself from grounded battery, through the right-hand winding of relay 118, inner armature and contact of said relay, resistance 119, normal contact of lower spring of key 115, ring of plugllO, ring of jack 11 1, conductor 202, right-hand winding of relay 200 to ground. Relay 200 is held energized due to this circuit and therefore the release of the connector switch does not take place until this plug 110 is removed from jack 11 1. Relay 118 also closed a circuit from grounded battery, through disconnect lamp 120, outer armature and front contact of relay 118 to ground. Lamp 120 is lighted and informs the operator that the parties are through conversing and that plug 110 should be removed from jack 11 1.

When the operator removes the plug 110 from the ack 114, the circuit of relays 118 and 200 is broken. Relay 118 deenergizes and opens the circuit of the lamp 120. Relay 200 deenergizes and opens the circuit of relay 203. After a short interval the relay 203 deenergizes and closes a circuit from grounded battery, through the righthand winding of release magnet 225, primary off-normal contact 226, left-hand armature and back contact of relay 203, right-hand armature and back contact of relay 203, armature and back contact of relay 200 to ground. Magnet 225 becomes energized and restores the connector switch to its normal position.

If the called line had been busy, ground would have been found upon the test terminal 211 thereof. The following circuit would then have been closed when the relay 2041 de'e'nergized after the second series of impulses: grounded battery through right-hand winding of release magnet 225, primary off-normal contact 226, inner lefthand armature and contact of relay 204, side-switch arm 21?, brush 21 1, terminal 211, to ground through a side-switch arm 217. Magnet 225 energizes and releases the connector switch. Magnet 225 at its righthand armature and front contact connects the busy tone 227 to the lower line conductor. T his busy tone is then transmitted to the calling subscriber in the well-known manner. If thecalling subscriber then immediately replaces his receiver upon the switchhook, release takes place substantially as described.

Magnet 225 at its left-hand armature and front contact completed a locking circuit for itself from grounded battery, through the right-hand winding of relay 121, inner right-rand armature and front contact of relay 106, sleeve of plug 110, sleeve of jack 114e, conductor 228, left-hand armature and front con act of relay 203, primary off-non mal contact 229, left-hand armature and front contact of magnet 225, left hand winding of magnet to ground. Relay 121 energizes and closes a locking circuit for itself from grounded battery, through the left-hand inding of relay 121, lefthand armature and front contact of relay 1 1 left-hand armature and contact of re- H 00, left-hand armature and front conact of relay 106 to ground.

Relay 121 at its right-hand armature and contact closes a circuit for lamp 108 and lamp 108 becomes lighted. If therefore the calling subscriber fails to immediately restore his receiver upon its switchhook as soon as he receives the busy tone, the lamp 108 remains lighted. The operator. seeing the lamp 108. depresses her listening key 111 and thereby associates her head set (not shown) with the calling line. if the calling subscriber should now fish to converse with some other line at the second oilice, he may so inform the operator. The operator will then actuate her sending device 117 in accordance with the number of the desired line if such line is served by the connector switch shown in 2, or if such line is served by a different connector switch. she will first remove the plug 110 from jack 114; and place it in a jack similar to jack 114: which is associated with the last mentioned connector switch. The operator will then depress her sending key 115 and oper ate her sending device 117 in the usual manner.

We will now assume that while subscribers lines 100 and 222 are connected for conversation, that the called party at subtation temporarily replaces his receiver upon the switchhook while he is looking up certain information or for some other reason. The circuit of relay 224 is opened and this relay deenergizes and completes a circuit from grounded battery, through winding of relay 230, outer ri ht-hand armature and contact of relay 204, side-switch arm 231 (position 4), armature and back contact of relay 224, armature and front contact of relay 200 to ground. This circuit is opened, however, when the slow-torelease relay 204 deenergizes after its circuit has been opened for a short interval at the frontcnntact of relay 224. The deenergization ofrelay 204 also opens at its outer left-hand armature and contact the circuit of the release magnet 225. When the called subscriber removes his receiver to resume conversation, relays 224 and 204 are energized in the ordinary way and since the slow-to-release relay 230 will have decnergized by this time the circuit for the release magnet 225 is opened at the armature and contact of the relay 280.

. If, however, the parties are through conversing and the calling party wishes to establish a connection to another party in the called exchange, he requests the called party to transmit a series of impulses. These impulses may be produced in any well-known manner, as for example, by operating his calling device, or by moving his switchhook up and down several times. impulses cause the relay 224 to rapidly vibrate its armature. The first retraction of the armature of relay 224 closes the above traced circuit for relay 230 and opens the circuit of relay 204. But since relay 204 is made slow to release its armatures, its circuit is again closed at the armature and front contact of relay 224 before said armatures are retracted. At the same time a circuit is closed from grounded battery, through the right-hand winding of magnet 225, primary off-normal contact 226, outer left-hand armature and front contact of relay 204, armature and front contact of relay 230, armature and front contact of re lay 224, armature and front contact of rela 200 to ground. 1

Release magnet 225 energizes and release the connector switch in the well-known manner. Magnet 225 at its left-hand armature and contact closes a locking circuit for itself from grounded battery through the right-hand winding of relay 121, inner right-hand armature and front contact of relay 106, sleeve of plug 110, sleeve of jack 114, conductor 228, left-hand armature and front contact of relay 203, primary offnormal contact 229, left-hand armature and contact of magnet 225, left-hand winding These self from grounded battery, through the left-hand winding of relay 121, left-hand armature and front contact of relay 121, left-hand armature and contact of relay 109, left-hand armature and front contact of relay 106 to ground. Relay 121 also closes a circuit for lamp 108 from grounded battery, through lamp 108, right-hand armature and front contact of relay 121 to ground. Lamp 108 becomes lighted. The operator seeing the lighted lamp 108, listens in and ascertains the new number in the usual way. Since the establishment of this new connection is substantially the same as that above described, further description is deemed unnecessary. 7

It will now be assumed that the calling subscriber 100 operates his sending devlce so that the selector switch 102 selects the trunk terminating in the repeater circuit shown in Fig. 8. A circuit is then closed from groundedbattery, through the left-hand winding of relay 104, lower left-hand winding of repeating coil 105, over the calling line circuit previously described, upper lefthand winding of repeating coil 105, righthand winding of relay104 to ground. Be lay 104 energizes and completes a circuit from grounded battery through winding of slow-to-release relay 106, left-hand armature and contact of relay 104 to ground. Relay 10 4' becomes energized and closes the trunk 112, 113 which extends to the selector switch 125 at the second exchange. The closure of the trunk 112, 118 completes a circuit of the line relay (not shown) of the selector switch 125. The subscriber at substation. 103 now operateshis sending device to send out another series of impulses. The selector switch will be operated in the usual manner by this series of impulses to select a particular group of trunks and then to automatically hunt for an idle trunk in such group. These trunks lead to connector switches similar to that shown in Fig. 2. As soon as the selector switch 125 selects an idle trunk, the line relay 200 of the connector switch is energized over a circuit from grounded battery, through the lefthand winding of relay 200, conductors 201. 201', upper brush of selector switch 125, conductor 112, upper right-hand winding of repeating coil 105, armature and con tact of relay 106, right-hand armature and contact of relay 104", lower right-hand winding of repeating coil 104, conductor 113, middle brush of selector switch 125, conductors 202 and 202, right-hand wind ing of relay 200 to ground. The calling subscriber now operateshis'sending device twice. In response. to these two series of impulses the connector switch operates to establish a connection to the called substation 222 in exactly the same manner as above described when it was controlled by the operator.

It will now be assumed that the calling subscriber 100 wishes to converse with another party in the second exchange as soon as he is through talking with the first party. He, therefore, requests the called party to operate his dial or move his switchhook up and down several times, thereby transmit ting impulses to the line relay 224. In re sponse to this operation of the line relay 224, the circuit of the release magnet 225 is closed in the manner described. Magnet energizes and releases the connector switch in the manner described. Magnet 225, by attracting its left-hand armature, connects ground to the selector switch 125 over the conductors 228, 228. This ground energizes the release magnet (not shown) of the selector switch 125 in the well-known manner, whereupon the selector switch 125 is restored to its normal position. The calling subscriber may now reoperate the selector switch 125 and a connector switch similar to that shown in Fig. 2, by transmitting three series of impulses. It will thus be observed that the calling subscriber does not have to build up a complete connection, but merely has to reset the switches at the second exchange.

What is claimed is:

1. In a telephone system, a calling subscribers line, a called subscribers line, means including automatic switches for establishing a connection between said lines, means for producing long and short interruptions in the called subscribers line, means op erated in response to a short interruption of said called line for restoring certain'of said automatic switches, and means operated in response to a long interruption of such called line for'preventing the operation of said last mentioned means.

2. In a telephone system, a calling subscribers line, a called subscribers line, means including automatic switches for establishing a connection between said lines, means for producing long and short interruptions in the called subscribers line, release means operated in response to a short interruption of said called line for restoring certain of said automatic switches, and means operated in response to a long interruption of such called line for preventing the operation of said release means.

3. In a telephone system, a calling subscribers line, a called subscribers line, means including automatic switches for establishing a connection between said lines, means for producing long and short interruptions in the called subscribers line, a re lease magnet, a relay for controlling said magnet, means including a relay for energizing said first mentioned relay upon the opening of the called line, a slow-to-release relay, a circuit for such slow-to-release relay extending through contacts of said second mentioned relay, and a circuit for said release magnet extending through contacts of all of said relays.

4:. In a telephone system,- a calling subscribers line, a called subscribers line, means including automatic switches for establishing a connection between said lines, means for producing long and short interruptions in the called 'subscribers line, a release magnet, a relay for controlling said magnet, means including a relay for energizing said first mentioned relay upon the opening of the called line, a slow-to-release relay, a circuit for such slow-to-release relay extending through a contact of said second mentioned relay, a circuit for said first mentioned relay extending through a contact of said slow-to-release relay, and a circuit for said release magnet extending through contacts of all of said relays.

5. In a telephone system, a calling subscribers line, a called subscribers line, means including automatic switches for establishing a connection between said lines, means for producing long and short interruptions in the called subscribers line, a release magnet, a relay for controlling said magnet, means including a relay for energizing said first mentioned relay upon the opening of the called line, a slow-to-release relay, a circuit for such slow-to-release relay extending through a front contact of said second mentioned relay, a circuit for said first mentioned relay extending through a front contact of said'slow-to-release relay, and a circuit for said release magnet extending through front contacts of all of said relays.

6. In a telephone system, telephone lines, ofiices wherein said lines terminate, means including automatic switches at two oflices for connecting a line in one office with a line at the other of such oflices, means for producing long and short interruptions in the called line, means operated in response to a short interruption of said called line for restoring the automatic switches at the called office, and means operated in response to a long interruption of such called line for preventing the operation of said last mentioned means.

7. In a telephone system, a calling line, a called line, a link circuit for interconnecting said lines, a signal associated with said link circuit, means for connecting said calling line to said link circuit, means operated by such connection for operating said signal,

and means controlled by the called line for reoperating said signal.

8. In a telephone system, a. calling line, a called line, a link circuit for interconnecting said lines, a signal, circuits for said signal, means for connecting said calling line to said link circuit, means operated by such connection for closing a circuit for said signal, means for openlng said circuit, and means controlled by the called line for closing another circuit for said signal.

9. In a telephone system, a calling line, a called line, anoperators position, a signal at said position, circuits for said signal, means for connecting said calling line to said position, means operated by such connection for closing a circuit for said signal, means including automatic switches for extending said calling line from said position to said called line, and means controlled by said called line for releasing said automatic switches and for closing another circuit for said si nal.

10. n a telephone system, a calling line, a called line, an operators position, a line signal associated with said calling line at said position, means controlled by said calling line for operating said line signal, and

ing automatic switches for'extending said calling line from said operators position to said called line, means operated by the establishment of the first mentioned connection for displaying said signal, and means operated by the called line for releasing the automatic switches between the operators position and the called line and for displaying said signal.

In witness whereof, 'I- hereunto subscribe my name this 21st day of March A. D., 1918.

CHARLES L. GOODRUM. 

